The purpose of grain carts is to improve the efficiency of harvesting equipment such as combines, thereby shortening harvest time. While modern combines are fast and efficient, problem occur in transporting the grain away from the combine and out of the field.
Anytime the combine is stopped for unloading, valuable cutting time is lost--up to one-third of the machine's total capacity. This translates quickly into dollars lost. When a large combine is working in a 150 bushel per acre corn field, it can produce approximately 2,700 bushels per hour. But if required to stop and unload, this potential can be cut to as little as 1,688 bushels hourly. The loss of 1,000+ bushels of production per hour will multiply to a staggering 10,000 bushel loss in a ten hour workday. This problem of lost production is even more significant when smaller combines are used.
Loss of combine production is not the only difficulty faced by the farmer during harvest. Large trucks are sometimes used to transport grain from the field, but they often do not perform well in muddy or rough field conditions. Furthermore, in wheat country, a truck in the field can easily spark a catastrophic fire.
Grain cans are a solution to these problems. Grain cans usually comprise a grain hopper or box sitting atop a wheeled frame, in combination with an auger means or mechanism for unloading grain from the hopper. Productivity rises dramatically with the use of grain carts because combines need never stop to unload. Rather, grain from the combine bin is unloaded into the grain cart on the go. Moreover, a single grain cart can usually service one or more combines, first unloading one, then another, and transporting the harvested grain to a waiting truck whenever necessary. Grain carts also handle soft or rough fields with ease, and, since they are pulled behind a tractor, fire hazards are eliminated.
Because they offer a combination of economy, versatility, production savings, and maneuverability, grain cans have been widely accepted by the farmer and widely produced by equipment manufacturers. Yet there remain troublesome obstacles to overcome in grain can construction. It is the purpose of the present invention to surmount these obstacles.
One problem commonly encountered by grain can operators is a difficulty in visually determining the position of the auger mechanism. Most grain cans have auger mechanisms that include a folding grain conduit. Determining the position of the grain conduit is important in preventing damage to the conduit and hopper. The grain conduit is normally folded and unfolded a number of times a day. If the tractor operator cannot determine the position of the grain conduit from the driver's seat, he must jump off and on the tractor to check the conduit's position, wasting time and risking injury. Attempts have been made to solve this problem on cans that have augers that fold down the side of the hopper through the use of auger position indicators, but these indicators may fail and can be difficult to see due to dirt or wear.
Another common problem with grain carts is that the grain conduit protrudes, when in the folded, transport position, past the rear of the hopper. This creates a driving hazard, both for the tractor operator and road and highway users, and increases the chance of damaging the auger mechanism when the cart is maneuvered in fight areas.
The prior devices also have auger mechanisms that extend through a wall of the hopper such that there is auger structure contained inside the grain hopper. This internal auger structure can significantly impair grain removal from the hopper by hindering downward grain flow, by leaking grain into the sump causing a high start-up torque, and by lessening the depth of the hopper sump area. The auger mechanism may also include hydraulic cylinders and the like which leak and contaminate the grain. The fact that these mechanisms are located within the hopper makes routine maintenance more difficult, and, in the case of a hydraulic failure of the shut off mechanism when the cart is loaded, it is impossible to unload the cart with the auger.
Two types of drive systems are used in today's carts--PTO, or power take-off, and hydraulic drives. A problem arises if it is desired to change between the two, such as due to tractor failure. If, for example, a grain cart was last used with a PTO mechanism, to change to hydraulic drive the operator would be required to crawl under the cart to disengage the cart's PTO drive mechanism from the auger gear box and install a hydraulic drive. The same is true to go from hydraulic drive back to PTO. This, of course, is very time consuming. Still further, some systems do not provide a type of drive system that allows the operator to easily vary the rotational velocity of the unloading auger.
Along the same line, problems are often encountered in coupling grain carts and other implements to tractors and pulling vehicles. Normally an implement will have a single tang hitch or a clevis hitch for connection to the tractor. If the implement hitch is not complementary to the tractor hitch, either the implement hitch or the tractor hitch must be removed and replaced before hook-up.